code: def test_manual_input_spec(self):
      inputs = Input(shape=(None, 3))
      outputs = layers.Dense(2)(inputs)
      model = Functional(inputs, outputs)
      model.input_spec = InputSpec(shape=(None, 4, 3))
      with self.assertRaisesRegex(
          ValueError,
          r"expected shape=\(None, 4, 3\), found shape=\(2, 3, 3\)",
      ):
          model(np.zeros((2, 3, 3)))
      model(np.zeros((2, 4, 3)))
  
imports: import warnings
  import numpy
  import pytest
  from keras import backend
  from keras import layers
  from keras import testing
  from keras.layers.core.input_layer import Input
  from keras.layers.input_spec import InputSpec
  from keras.models import Functional
  from keras.models import Model
label_desc: Use image node_id 16 for calling the FunctionalTest obj's underlying member method code with example usage: obj.test_manual_input_spec() without return types